Water heater



Sept. 5,`1936.

c. B. GAMBLE WATER H'EATER Filed July 21, 1933 INVENTOR [/tar/65 ,3. &Jm ble ATTORNEYS Patented Sept. 15, 1936 'UNITED STA'TES PATENT OFFICE Charles B. Gamble, Birmingham, Ala.

Application July 21, 1933, Serial No. 681,506

2 Claims.

My invention relates to a water heater of the side arm type in which the tank is provided with an external circuit including a heating coil subject to the action of any suitable burner.

' Water heaters of this type have long been in accepted use, automatic mechanism having been applied for raising and lowering or 'extinguishing the burner responsive to the establishment of a i predetermin'ed temperature at a selected level in 4 proved in respect of their readiness to serve, their efficiency of operation, and their flexibility as to Capacity of hot water output.

One object of my invention is to prevent a reverse circulation being set up in the external circuit after the burner is cut off, it being apparent that an updraft of cold air circulating over the heating coils will convert them into radiators chilling the water-in the external circuit and. setting up a reverse circulation which will draw hot water' from the top of the tank and after chilling 2 it in the coil will return it to the bottom of the tank. I have conceived that by establishing a thermal balance between the water in the tank and the water in the external circuit which includes the heating coil a lock can be produced 4 which will prevent this objectionable reverse circulation and 'retain the hotwater in the tank.

I have further conceived that a more efiicient action can be obtained out of the heater itself by. so designing and arrangingits coils as to provide for a downfiow of water in an outer coil to take up heat 'from upflowing gases and to deliver the preheated water .at the bottom 'of an inner coil through which it flows concurrently with the hottest gases to the outlet line. I thus provide a 'heater so constructed as to secure counterflow heat transfer that will reduce the temperature of the wast'e gases to` a minimum and discharge wat-er into the tank at the temperature desired for use.

I have further conceived that the coils in the heater, so arranged and so connected to the tank, will not disturb the .thermal balance when the heat input is discontinued.

My invention further contemplates so conducting the hot water discharged from the inner coil as to protect it from effective heat interchange relationship 'with the cooler gases as they rise through the upper portion of the outer 'coil in a countercurrent flow with the descending cold water in said outer coil. Where the inner coil is materially shorter than the outer coil the most intense action ofthe heating means can be concentrated upon it and the water therein brought to a temperature which is substantially above the exit temperature of the products of combustion as they rise about the outer coil to the discharge, and my'preferred means' for preventing the loss of heat from the hot water outlet to theescaping gases is a batfie or deector means preferably associated with insulaticn-and which are adapted not only to insulate the cutiiowing hot water but to deflect the gases `so thata Very efiective heat interchange relationship will be obtained between them and the coldest water in the outer coils. In practice, with the water entering the outer coils at 52 F. and being discharged from theinner coils at 175? F., I have taken tempera ture readings on the exitgases and found them below 100 F. By thus -protecting the hot water outlet pipe within the heater it is subject to heat lcss only in the 'short radal `connection leading from the insulating'jacket to the tank insulation and the loss at this point is negligible. V My invention further contemplates the provision of an automatic-control of the water heating operation so as to prevent the temperature of the water being raised above that atwhich precipitation of its dissolved solide occurs, and to this end it is proposed to provideta regulator, adjust able to produce the predetermined water temperature by so varying the resistance in the dis--` charge line from theheater that the water in a single pass through the 'heater will attain the temperature desired for` use and yet will be held safely below that at which precipi-tation of its solids would occur. My regulator acts to decrease resistance in .the hot water outlet line as the thermal head decreases responsive to storage of hot water inthe tank. 1 This will regulate the volumetric fiow through the' heater, and, regardless'of the initial temperature of the water being heated or fluctuations inheat input to the coil, will supply hot water at the predetermined constant temperature desired to the tank.

My invention further comprises the novel details of Construction and arrang ements of parts, which in their preferred 'embodiments only are illustrated in the accompanying drawing which forms a part of this application, and in which:-

Fig. 1 is a view in side elevaticn of a side arm water heater with the tank shown in VerticaLcentral cross section; I i

Fig. 2 is an enlarged vertical sectional view through the water heater and regulator;

Fig. 3 is a fragmental sectional' view taken on the line III- III of Fig. 1.

Similar reference numerals refer to similar parts throughout the drawing.

In the embodiment of my invention illustrated which presents a simple type of side arm heater with a single coil and burner, I show conventionally a hot water tank l 0 having an insulating jacket H of any suitable character, a cold water supply pipe |2 leading downwardly to a point near its bottom, and a hot water discharge'pipe |3 leading from its top to the service mains.

The tank is provided with an external circuit comprising a pipe I 4 leading radially from the bottom of the tank and merging tangentially into the upper end of the outer heater coil !5 which at its lower end merges into an inner coil !6 which tapers upwardly and terminates in a dis'charge pipe IT leading vertically through an insulation chamber |8 and thence laterally into the regulator |9 whence the hot water flows through the outlet line 20 into the top of the tank.

It is a distinctive feature of my invention that this outlet line 20 is laid in the tank insulation I i and against the tank wall in such manner as to establish a temperature balance between the water in the tank and in the pipe 20 when the heat induced circulation stops.

The coils |5 and !6 are mounted in the heater 2 l the top 22 of which is provided with marginal outlets 23 for the products of combustion and at its center supports the downwardly tapered shell l8a of the inner insulation chamber which has an inverted cone' bottom andis filled with suitable insulating material surrounding the pipe IT. An

outer insulation chamber is provided in the heater between an inner shell 24 and the outer wall of the casing and it extends from the burner level approximately to the upper level of the outer coil l5.

The base 25 of the heater may be of any standard design having a suitable burner 26 and pilot 21 associated therewith, the burner being disposed centrally under and adjacent to the base of the inner coil !6. The coils l6 have a closer pitch than the outer coils |5 and they may converge spirally so that their upper convolution will fit into the' bottom recess under the insulation shell lsa. The hot gases from burner 26 impinge directly upon these inner coils and pass between them into contact with the outer coils, the products of combustion rising through the gradually restricted annular space between the shell l8a and lining 24 until they have all passed between the outer coils !6 and escape at the top of the heater.

'The pipe I 'l that Supplies hot water to the regulator l9 has an upturned serrated end 28. A bimetallic thermostat 29 is mounted in the casing with its free end overlying the pipe end 28 and an adjusting screw 30 acts to set it with relation to said pipe end. When it becomes heated by contact with the outfiowing hot water, it moves to decrease resistance in the outlet line 20 as the thermal head decreases due to storage of hot water in the tank.

The heater has an automatic gas'control comprising a thermostatic element 3| of any standard design in the tank which acts to control the valve 32 in the gas line 33 that Supplies burner 26. A suitable hand valve 34 is interposed in this line. It will be observed that the pipe !4 and the pipe that leads to the regulator IQ lie in substantially the same horizontal plane` The operation of the heater is as follows. Assuming the tank I 0 filled, the pilot 21 ignited, the valve 32 closed by hot water accumulated in the tank to the level of the thermostatic element 31, and the thermostat 29 engaging its serrated seat 28. As hot water is drawn from the tank the cold water level therein rises, the thermostatic element 3| reacts, the valve 32 opens and the burner 26 comes into play, directing hot gases initially against the inner coil IS with the products of combustion rising about the outer coil !5 to the top outlet from the heater. A circulation immediately results from the bottom of the tank through pipe I 4 downwardly through the outer heater coil !5, upwardly through the inner heater coil I6, and outwardly through the pipe ll past regulator 29 into the outlet line 20 and thence into the top of the tank.

If the inlet and outlet connections, leading from the heating coil to the tank and to the outlet line 20, were set at difi'erent levels there might be an unbalanced temperature head established, but by bringing these two connections so that the inlet connection opens into the tank at the level where the outlet line comes into beat interchange relation with the water in the tank, this is avoided and the water in the inner and outer coils being in thermal balance there will be no reverse circulation set up' in the heater. It, therefore, follows that I provide a complete lock against any reverse water circulation in the external circuit when heat is not being applied and as a result I hold all of the hot water that has been produced, in the tank and under the insulation jacket ready for use.

The regulator !9 will be so set that the water under treatment will not be so highly heated as to cause a precipitation of its dissolved solids, and I regard this a feature of very great practical importance in my improved water heater.

While I have shown my invention in but one form, it will be obvious to those skilled in the artthat it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:-

1. In a water heater, a double coil comprising t outer convolutions connected below to inner reversely pitched spiral convolutions which deliver into an outlet pipe substantially below the upper end of the outer coil, a burner the hot gases from which impinge directly against the inner convolutions, and a center deector surrounding the outlet pipe to defiect therefrom the products of combustion and direct them in counter-current flow upwardly about the outer coils.

2. In a water heater, an outer coil having down- Wardly pitched helical convolutions with an upper water inlet connection, an inner coil connected below to said outer coil and having upwardly pitched spiral convolutions extending upwardly part way through the convolutions of the outer coil to a hot water outlet pipe rising through the outer coil, a burner the hot gases from which impinge directly on the inner coil, and a body of insulation surrounding the outlet `pipe and serving to defiect the escaping products of combustion against and through the convolutions of the outer coil.

CHARLES B. GAMBLE. 

